1. FIELD OF THE INVENTION
This invention relates to an improved condition responsive electrical switch construction as well as to improved parts therefor and/or for other devices and methods of making such parts.
2. PRIOR ART STATEMENT
It is well known that condition responsive electrical switch constructions have been provided to each act as a "cold control" wherein the same is utilized to control the operation of a refrigerator or the like so that when the temperature in the refrigerator rises to a certain temperature, the control will operate an electrical switch to turn on the refrigerant compressor and continue to operate the refrigerant compressor until the temperature in the refrigerator has fallen a certain differential below the previously described high turn-on temperature whereby the control will cause the switch to turn off the compressor.
For example see the following four items:
(1) U.S. patent, to Grimshaw, U.S. Pat. No. 3,065,323 PA1 (2) U.S. patent to Howell, U.S. Pat. No. 3,096,419 PA1 (3) U.S. patent to Pursnani et al, U.S. Pat. No. 4,045,635 PA1 (4) Robertshaw Controls Company publication M D 12-C (Rev. 5/75) entitled "Robertshaw R C Series Narrow Differential Cold Controls" PA1 (5) U.S. Patent to Jorgensen et al, U.S. Pat. No. 3,609,270 PA1 (6) U.S. Patent to John, U.S. Pat. No. 3,656,081 PA1 (7) U.S. Patent to Andresen, U.S. Pat. No. 3,735,069 PA1 (8) U.S. Patent to Andresen, U.S. Pat. No. 3,735,080 PA1 (9) U.S. Patent to Aidn, et al, U.S. Pat. No. 3,819,896 PA1 (10) U.S. Patent to Aidn, et al, U.S. Pat. No. 4,027,131 PA1 (11) U.S. Patent to Piber, U.S. Pat. No. 3,548,131 PA1 (12) German Patent to Lorsbach, U.S. Pat. No. 1,266,387.
The prior known condition responsive electrical switch construction of item (4) above has a pivotally mounted lever for operating the electrical switch with the lever being pivotally moved by a movable wall of a condition responsive device that is opposed in the expanding direction thereof by a suitable range spring. The range spring includes a pin-like member that passes through a slot in the switch actuating lever so as to have its free end received in a complimentary recess formed in the movable wall of the condition responsive device, the lever being biased against an annular shoulder of the pin member so as to follow movement thereof.
The condition responsive electrical switch construction of items (1) and (2) above each appears to have a cradle-like member to transmit movement of the pin member of the range spring to the switch actuator lever.
The switch housing of item (4) above has two pairs of opposed locating ears received respectively in aligned slots of a housing casing and are held in place by a staking of the casing to deform side edges of the casing slots against adjacent side edges of the ears of the switch housing.
Each of the switch housings of items (1) and (2) above appears to have a single pair of opposed locating ears received respectively in aligned slots of a housing casing and each being wedged between an angled edge of its respective slot and a cooperating flat edge opposed thereto as a cover member is being pivoted into place on the housing casing and thereby camming against the switch housing and causing the switch housing and housing casing to move into the final assembled position thereof.
The electrical switches of items (1), (2) and (4) above each appears to have a single movable contact moved by a kicker of the aforementioned actuating lever relative to a single fixed contact whereas the electrical switch of item (3) above has a single movable contact disposed between a pair of spaced fixed contacts whereby the movable contact is moved between the fixed contacts by the aforementioned actuator lever.
It is also known to have two movable contacts disposed between the two fixed contacts of a similar electrical switch with the two movable contacts respectively being engageable with the fixed contacts and being controlled by the kicker of the aforementioned actuator lever.
It is also known to have a pair of movable contacts disposed on opposite sides of a fixed contact with an actuator member disposed between the movable contacts to respectively move one of the movable contacts away from the fixed contact while the other movable contact remains in contact with the fixed contact.
For example, see the following six United States patents:
It is also known to loop a switch blade to provide for a wiping action of the contact thereof with a fixed contact when the looped switch blade is moved by an actuator member in order to break a weld between the movable contact member and the fixed contact member.
For example, see the following two items:
Each of the condition responsive electrical switch constructions of items (1), (2) and (4) above appears to have the selector shaft thereof provided with a cam surface that engages against an abutment of the actuator lever to force the actuator lever against a stop when the selector shaft is rotated to an "off" position thereof.
Each of the condition responsive electrical switch constructions of items (1), (2) and (4) above appears to have the actuator lever thereof be provided with knife-edges which pivot against "vee" edges formed in the casing of the housing means thereof, item (2) appearing to have an additional lever cooperating with the actuating lever to reduce the bearing load on the "vee" edges of the casing.